Infusion pump devices and systems are relatively well known in the medical arts, for use in delivering or dispensing an agent, such as insulin or another prescribed medication, to a patient. A typical infusion pump includes a pump drive system which typically includes a small motor and drive train components that convert rotational motor motion to a translational displacement of a plunger (or stopper) in a reservoir that delivers medication from the reservoir to the body of a user via a fluid path created between the reservoir and the body of a user. Use of infusion pump therapy has been increasing, especially for delivering insulin for diabetics.
Continuous insulin infusion provides greater control of a diabetic's condition, and hence, control schemes are being developed that allow insulin infusion pumps to monitor and regulate a user's blood glucose level in a substantially continuous and autonomous manner. Regulating blood glucose level is complicated by variations in the response time for the type of insulin being used along with variations in a user's individual insulin response and daily activities (e.g., exercise, carbohydrate consumption, bolus administration, and the like). To compensate for these variations, the amount of insulin being infused in an automated manner may also vary. Reliance solely on currently sensed glucose values may result in delivery adjustments that are too late to avoid a hypoglycemic or hyperglycemic event, so accordingly, predictive algorithms may be utilized to provide estimations of the future blood glucose levels as an aid in regulating the blood glucose level.
One scenario that can be problematic occurs when a user consumes fast-acting carbohydrates, for example, to avoid a potential hypoglycemic event. This, in turn, can result in a spike in the user's blood glucose level, which, in turn, can result in a rising trend in glucose values indicating a need to deliver insulin to mitigate the rise in blood glucose level, thereby unintentionally counteracting the fast-acting carbohydrates. While a quick response time is desired to facilitate a stable blood glucose level, automatically recovering from responding too quickly may not be feasible since infusion devices are generally incapable of undoing a previous delivery. Thus, there is a need to distinguish actionable events that the infusion device should respond to from those that do not require an immediate response.